Heat exchanger



Dec. 17, 1929. R. o. HENSZEY 1,740,300

HEAT EXCHANGER Filed Dec. 12, 1928 I N VEN TOR.

Patented Dec. 17, 1929 PATENT OFFICE BOY 0. HENSZEY, OF OCONOMOWOC, WISCONSIN HEAT EXCHANGEB Application filed December 12, 1928. Serial 80. 825,451.

My invention relates to iinprovements in heat exchangers of the general ty e disclosed in my former applications, Serial 0. 725,531, filed July 11, 1924, Serial No. 17,413, filed March 21, 1925, and Serial No. 147,122, filed November 8, 1926.

The primary object of this invention is to provide for a substantially continuous deliver w condltions which will permit a delivery of such water through a, small pipe without danger of clogging and without precipitation on the interior surfaces of the pipe, such as would otherwise interfere with-heat transfer and eventually fill the pipe, and to accomplish these results while maintaining the highest possible conservation of heat by transfer of the heat units to the feed water and make u water.

Further o jects of myeinvention, as herein set forth, are to provide a heat exchan er in which the blow oil water will utilize the grit and other. impurities therein to scour the walls of the passa es through which such 5 water flows, instead 0 being deposited thereon, as is done in heat exchangers heretofore used; to provide means for minimizin the effect of destructive vibration, such as r sults from expansion, accelerating velocities, and

unbalanced pressures in blow off pi es receivin water from high pressure boi ers; to provi e means whereby the destructive cuttin and wire drawing effects upon the contro lin valves of blow off pipes may be substantia 1y eliminated; to provide a heat exchanger whose passages are so proportioned as to accomplish heat transfer with maximum efficiency from a small stream of blow off water into a larger stream or volume of feed 40 water; to provide means whereby the pressure of the blow off water may be progressive-' ly diminished from the boiler to a valve controlled outlet, before reaching which, such pressure will have diminished to the minimum consistent with effective delivery and the maintenance of asufficiently high velocity to counteract settling and precipitating tendencies and maintain scouring effects; and, in general, to rovide means for urifying 5c the water of a oiler continuously y allowof blow off water or concentrate under .showlng the end portions of a heat exchanger cylinder, drawn to a plane intersecting the feed water inlet and outlet ports.

Like parts are identified by the same referencebharacters throu out the several views.

Figure 1 shows diagrammatically a battery of boilers 10, which are each provided.

with a blow ofi pi 11, which leads to a header 12 connecte with the upper heat exchanger cylinder 13. It may be assumed that the feed water is delivered to the boilers by a pump 15 through pipes 16,130 the heat exchanger cylinder 13 and from that cylinder to the boilers through the pipes 17. The make up water is delivered from any suitable source so 0 sup 1y throu h a pipe 18, which: conducts it to t e lower eat exchanger cylinder 13". From that cylinder the water passes through a pipe 19 to the pre-heater 20 and thence to the pump 15 through the pipe 21. All of the parts thus far described may be assumed to conform to ordina practice in structureand arra-n ment. urther description is therefore eemed unnecessary.

The heat exchanger com rises a cylinder 13 for the feed water, a cylin er 13 for the make up water, and similar associated interior structure and pipe connections for the respective cylinders. The interior construction of the cylinders 13 and 13 is substantially the same and therefore Fi re 3 may be taken as illustrative of either. at in illustrating the pipe connections, Figure v3 is assumed to represent the feed water heat exchanger and 1 therefore the reference character 13 is ap- 100 plied to the outer cylinder wall, and the inlet and outlet ports for the feed water are indicated at 22 and 23 respectively. The pipe 16, shown in Figure 1, connects with the port 22 and the pipe 17 leads from the port 23. The cylinder 13, shown in Figure 3, is connected at its respectiveends to header or cap members 24 and 25 by means of collars 26, threaded to the respective ends of the cylinder 13. The header members 24 and 25 are each bolted to an associated collar 26, whereby, when the bolts of the header member 24 are removed, this member and associated parts hereinafter described, may be withdrawn from the cylinder 13.

The cylinder 13 has similar header members, as shown in Figure 2. This cylinder has .its inlet port 22 connected to any suitable source of supply of water not previously used in the system, and which is used to compensate for water and steam leakage, and that otherwise discharged from the system, including the blow off water which is withdrawn to prevent undue concentration of impurities.

It will be observed that the header members 24 and 25 are provided with interiorly projecting tapered bosses 30, which receive the ends of an inner cylinder 31. This inner cylinder is secured to the boss 30 of the header member 24 by a cross pin.32, and it preferably has a water tight fit upon the tapered bosses 30, the surfaces being ground true. The water entering throu h the nlet port 22 will therefore be received in the annular space between the c linders 13 and 31, and will flow longitudina ly in this annular space to the outlet port 23, which is preferably located on the other side of the cylinder 13 from that'having the inlet 22. At one side of its-boss 30 the header member 24 has a threaded aperture, which receives a sleeve 35 through which a nipple 39 extends. This nipple receives the end of a tube 36 and is welded thereto. The sleeve 35 has an exteriorly threaded outer end portion 37, which receives a packing nut 38, whereby the joint between the nipple 39 and the sleeve 35 may be protected against leakage by suitable packing. A portion of the ipe 36 within the cylinder13 is coiled about t e inner cylinder 31, as clearly shown in Figure 3, and its other end portion 40 is fitted at 41 within a similar nipple 42 which passes through a sleeve 43, similarly constructed and rovided with a packin joint, as above descri ed with reference to t e coupling member 35.

The helically coiled portion of the pipe 36 is spaced from the inner cylinder 31 by one or more mounting strips 46. Preferably three of these strips are employed and disposed longitudinall of the inner c linder 31 in symmetrical re ation thereto, 1. e.these strips are preferably equidistant from each other. The successive helical coils of the pi 36, are secured to these stri s 46, where y they are spaced from each at er and from the support- In the construction illustrated, the cylinder 13, shown in F i re 2, is the feed water cylinder and the c linder 13 is the make up water cylinder. T e blow off water from the header pipe 12 vwill be delivered through the nipple 42 to the coiled pipe 36 contained this pipe 36 the blow off water will be received by a connecting pipe 50 and conveyed through the nipple 42 of the lower cylinder 13, and through the coiled pipe 36" of that cylinder, to the pipe connections 52 leading through the casing of a control valve '53, to an outlet at 54, which discharges into a drain, indicated at 55. An automatic valve 56 having a diaphragm control at 57 may regulate the quantity of blow of! in proportion to the volume of make up water as describedin my co-pending applications.

In the cylinder 13 a portion of the heat of the blow off water will, of course, be transwithin cylinder 13. From the outlet end of ferred to the feed water, the temperature of the feed water ,being. lower than that of the boiler water. The length of the cylinder 13 and of its contained coil of pipe 36 issuch that substantially all of the heat units which can be transferred to the feed water in this manner will have been transferred before the blow off water passes out ofthecylinder to the connecting pipe 50.

A similar transfer of heat units will then be effected within the cylinder 13* to the cooler make u jwaterof the latter" chamber,

so that when t e blow off water reaches the outlet pipe 52, it willhave iven 'up substantially all of the heatunits w ich, within prac-- tical limits, can be returned to the boiler. lts tem erature will have been reduced to nearly t at of the make up water.

Aside from the structural features above described, my invention has the following novel characteristics: The coiled pipes 36 and 36 are proportioned in diameter and len h to the estimated quantity of water to be lown off under. the normal b'oiler pressures, and the normal quantities of feed water and make up water to be injected intolthe boilers. In calculating the length .and diameter of each pipe 36 and 36, the friction loss within each pipe is taken into consideration and these pipes are made long enough to largely absorb 1 the boiler pressure in" friction loss, while retaining sufiicient pressure and kinetic energy at all stages to maintain a pipe scouring velocity.

The friction being uniform, it will be obvious that the pressure reduction will be constant and so graduated at all stages, that there will be no conversion of this water into steam at any stage of its passage throu h the pipe. Heat transfer is more efiicient y accomplished by having the heating liquid circulate at a high velocity and correspondingly increased frictional ressure, not only because of the scouring e ects, but also by reason of the constant substitution of particles of liquid from the central portion of the stream for those that have given up their heat to the wall of the tube. If the flow of heating liquid through a tube is slow, the film or layer in actual contact with the tube is cooled and tends to insulate the wall from the hotter liquid in the central portion of the stream, thus reducing the rate of heat transfer.

The friction losses in such coils of pipe are easily determinable from engineering data available to those skilled in the art to which this invention pertains, and the required length and diameter of the coiled pipe and of the annular chamber in which it is located can thus be made to readily conform to the requirements for any given boiler pressure, and to satisfy the average blow ofi requirements for each system, after determining the ordinary rate of water consumption and the degree of its purity. The rate of heat transfer into the feed water and into the make up water is also determinable from engineering data, after ascertaining the relative temperature of the heating liquid within the coil and the heat absorbing liquid exterior thereto.

For example, in a system having 100 pounds per square inch of boiler pressure and requiring the addition of 3600 gallons of make up water per hour, and an equivalent volume, or more, of feed water, I provide cylinders 13 and 13, which are each approximately 12 feet in length, 6 inches in diameter, and having an annular coil receiving water circulating chamber of approximately 1 inches in width, or distance from the outer cylinder wall to the inner cylinder wall. Associated with such cylinders, I employ coiled blow off pipes 36 and 36, each of approximately 150 feet in length and ,4; inch inside diameter.

By so constructing the heat exchanger, I am able to leave the outlet valve 53 continuously open under normal conditions of op eration with a resulting delivery of ten gallons per minute of blow oil water at a velocit which causes the impurities to scour the interior surfaces of the pipes, with no tendency for the impurities to precipitate thereon, or to settle at any point. When the blow ofi valve 53 is closed, the boiler pressure will, of course, extend throughout the entire blow off line, including pipes 36 and 36'. But as soon as the valve is opened, the pressure of the liquid at the end of the pipe 36" will be very greatly reduced thus greatly reducing the wear on the valve seats and exposed surfaces within the valve casings. The erosion may be ap roximately that required to keep the sur aces clean and free from deposits.

The automatic valve 56 or the hand valve 53 may reduce the flow at times, but when it again opens any sediment, or any incipient deposit will be immediately blown and scoured out.

Owing to the slight reduction. in pressure for each foot of blow off pi e, the tendency to vibrate is also greatly re uced. Such vibration, as occurs in the coils, is absorbed by the supporting cage bars, or spacing members, 46, and the coils being welded to these bars, any resulting wear occurs between the bars and the supporting tube 31, which can easil be renewed at small cost by removing the eader member 24, as heretofore explained.

It will be understood from the drawings that the water in the supply duct or ducts will flow in a direction opposite that taken by the blow of! water, in accordance with common practice, and in order that the progressively cooling blow off water may transfer its heat to the feed water or make up water of correspondingly lower temperature.

I claim:

1. In a heat exchanger, the combination with a boiler, of a boiler supply duct, a blow ofl duct leadin from the boiler through the supply duct, an provided with an outlet, said blow off duct being of such length in proportion to its diameter as to absorb a ma1or ortion of the pressure of the boiler water in fi'iction loss, and thereby control the volume independentl of valve control, whereby accumulation o sediment and precipitation within the duct may be revented.

2. In a heat exc anger, the combination with a boiler, of a water suppl passage leading thereto, a helically coile blow off duct leading from the boiler to a normally full open waste delivery outlet and said helically coiled duct having a portion thereof within the supply passage, said blow of! duct being of a length and diameter suflicient to absorb such pressure as is required to deliver the desired quantity of concentrate at a scouring velocity.

3. In a heat exchanger, the combination with a boiler, of a water supply passage leading thereto, a helically coiled blow ofi duct leading from the boiler to a suitable waste delivery outlet and having a helically coiled portion within the supply passage, said blow off duct being of a length and diameter sufficient to absorb the boiler pressure in fric- 5 ing a total area adequate to romote an effective transfer of its availab e heat units to the boiler supply Water.

ROY O. HENSZEY. 

